1. Field of the Invention
The present invention relates to an electronic part. More particularly, the present invention relates to an electronic part having a non radiative dielectric waveguide and integrated circuit using the same which are used in a microwave or millimeter-wave radar for example.
2. Description of the Related Art
As shown in FIG. 2, a conventional transmission line for a millimeter wave or a micrometer wave, has two parallely opposing conductive plates 1, 2 and a dielectric strip 3 disposed between the conductive plates. A normal type non radiative dielectric waveguide ("normal NRD") is a kind of transmission line. The distance a2 between the conductive plates is adjusted to be equal to or less than a half wavelength of a wavelength of an electromagnetic wave so that the electromagnetic wave propagates only in the strip line 3.
A millimeter wave module that uses tie NRD guide is constituted by integrating each of the components, such as an oscillator, a mixer, and a coupler, but originally, the normal NRD guide has been used as the NRD guide of each component.
On one hand, in the normal NRD guide as mentioned above, there has been a problem such that since a transmission loss is occurred by a mode transformation of the LSM01 mode and the LSE01 mode in a bend part, it makes it impossible to design a bend having an arbitrary radius of curvature, and for preventing the transmission loss by the above mentioned mode transformation, the radius of curvature in the bend part can rot be made smaller, thereby the module as a whole can not be miniaturized. Accordingly, as shown in FIG. 1, it has been developed a NRD guide (hereinafter, it refers to as a hyper NRD guide) that is configured to form the respective grooves in the facing planes of the conductive plates 1, 2, and to place a dielectric strip 3 between the grooves, thereby transmitting a single mode of the LSM01, and it is disclosed in laid-open Japanese Patent Application No. 9-102706.
It makes possible to design a bend with a little transmission loss and having an arbitrary radius of curvature according to the above mentioned hyper NRD guide, thereby resulting in an advantage of miniaturizing the module as a whole. However, in general, the transmission loss is less in the normal NRD guide if not considering the transmission loss with the above mentioned mode transformation in the bend part.
Further, when constituting a single millimeter wave module by combining the above mentioned components, a positional displacement is inevitably occurred in either a propagation direction of tie electromagnetic wave or a direction perpendicular to the propagation direction of the electromagnetic wave, at the connection plane of the conductive plate and the dielectric strip, according to a dimensional accuracy for each of the respective components and an assemble accuracy of the respective components, and also an amount of that positional display varies. In a normal NRD guide, the reflection loss is lower at the connecting portion in comparison with a hyper NRD guide. Similarly, transmittivity of electromagnetic wave is high at the connecting portion.
Also, in the coupler for example, an excellent characteristics may be obtained without requiring a high dimensional accuracy since using the normal NRD guides as two NRD guides placed with a predetermined space the electric field energy distribution spreads wider than tie case of using the hyper NRD guide.
Further, when constituting an oscillator by coupling the dielectric resonator with the non radiative dielectric line, in general, the normal NRD guide is more appropriate since the normal NRD guide can easily and strongly couple the dielectric resonator and the non radiative dielectric line.